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At least 73 records · Page 4Linked to original sources
PubMed2026

Quantifying the evolutionary potential for Delta Smelt persistence in a warming habitat.

Long-term persistence of managed species will depend, in part, on whether the species harbors the physiological or genetic potential to adjust to warming temperatures, and whether relevant genetic variation is modified by management practices. The critically endangered Delta Smelt (Hypomesus transpacificus) is intensively managed, but little is known about the presence of genetic variation for resistance to elevated temperature, which will be important to maintain for their persistence in a rapidly warming future. Using a pedigree and whole genome sequencing data, we characterized the genetic variation and genomic architecture for CTMax (as a metric of upper thermal tolerance) across control and elevated rearing temperatures, alongside covarying traits (body size, degree of hatchery ancestry). Warmer rearing temperatures increased CTMax through acclimation but also resulted in reduced additive genetic variation for the trait, which could constrain adaptation under thermal stress. We found that larger fish had reduced CTMax, although this effect was diminished at elevated temperatures. We observed modest heritability for CTMax at rearing temperatures of 15°C and 18°C (0.26 and 0.16, respectively), but only a limited number of loci were identified that had consistent effects on CTMax across rearing temperatures. Instead, the genomic basis of thermal tolerance was highly dependent on rearing temperature (many loci detected with a GxE effect). The influence of domestication selection was indicated by changes in allele frequency, and divergence in upper thermal tolerance and plasticity, between low and high hatchery ancestry groups. Minimal overlap between loci associated with domestication and CTMax suggests that these traits possess separate genetic underpinnings. Knowledge of genetic variation supporting ecologically relevant physiological variation may be useful for refuge management and may inform supplementation in an ever-warming environment.

conservation physiology↗
PubMed1989

[Interactions between prolactin with its receptor].

The prolactin (PRL) receptor has recently been sequenced. The rat PRL receptor is a linear glycosylated polypeptide of 291 amino-acids. The major part of the molecule is located on the external part of the cellular membrane. Recently, a larger form of the receptor has been evidenced in rabbit, and man, which presents some partial structural homology with the sequence of the growth hormone receptor. The PRL receptor, distributed in various tissues, is located in equivalent quantities in the peripheral and internal membranes of the cells. The transduction mechanism(s) from the activated receptor to the genes controlling the expression of different prolactin-induced-proteins is not yet well understood. Prolactin is the main hormone involved sequentially in the down and up-regulation of the PRL receptors number. Such a long-term induction of receptors by PRL is evidenced under physiological conditions such as pregnancy and lactation. The recent demonstration of different molecular forms of PRL generated after the transduction of the hormone (glycosylated PRL, cleaved PRL, 16K fragment) introduces the hypothesis that the interaction between the hormone and its receptor is probably more complex. These different prolactins are still capable of binding to the receptor and their biological activities are more or less conserved. The physiological or pathological significance of such an heterogeneity of the PRL molecule needs to be further confirmed.

Animals↗
PubMed2026

Quantifying the Evolutionary Potential for Delta Smelt Persistence in a Warming Habitat.

Long-term persistence of managed species will depend, in part, on whether the species harbors the physiological or genetic potential to adjust to warming temperatures, and whether relevant genetic variation is modified by management practices. The critically endangered Delta Smelt (Hypomesus transpacificus) is intensively managed, but little is known about the presence of genetic variation for resistance to elevated temperature. Using a pedigree and whole genome sequencing data, we characterized the genetic basis of CTMax (as a metric of upper thermal tolerance) across control and elevated rearing temperatures, alongside covarying traits (body size and degree of hatchery ancestry). Warmer rearing temperatures increased CTMax through acclimation but also resulted in reduced additive genetic variation for the trait. We observed modest heritability for CTMax at rearing temperatures of 15°C and 18°C (0.26 and 0.16, respectively), but only a limited number of loci were identified that had consistent effects on CTMax across rearing temperatures. Instead, the genomic basis of thermal tolerance was highly dependent on rearing temperature (i.e., many loci detected with a GxE effect). This temperature-dependent genomic architecture is consistent with our finding that additive genetic variation for CTMax was reduced under warmer rearing conditions, indicating a potential constraint on adaptive evolutionary change. The influence of domestication selection was indicated by changes in allele frequency, and divergence in upper thermal tolerance and plasticity, between low and high hatchery ancestry groups. Minimal overlap between loci associated with domestication and CTMax suggests that these traits possess separate genetic underpinnings. Knowledge of genetic variation supporting ecologically relevant physiological variation may be useful for captive management and may inform supplementation of fish to the wild in an ever-warming environment.

conservation physiology↗
PubMed1975

Renal conservation of ketone bodies during starvation.

Renal handling of acetoacetate and beta-hydroxybutyrate was studied in 12 obese subjects undergoing total starvation. Simultaneously, the acetoacetate, beta-hydroxybutyrate, and inulin clearance rates were measured, and acetoacetate and beta-hydroxybutyrate reabsorption rates were calculated. Renal clearance of blood acetoacetate and beta-hydroxybutyrate remained constant. In contrast, acetoacetate reabsorption rate increased significantly from 47 plus or minus 10 mumoles/min on day 3 to 106 plus or minus 15, 89 plus or minus 10, and 96 plus or minus 10 mumoles/min on days 10, 17, and 24, respectively. Similarly, beta-hydroxybutyrate reabsorption rate increased significantly from 154 plus or minus 27 mumoles/min on day 3 to 419 plus or minus 53, 399 plus or minus 25, and 436 plus or minus 53 mumoles/min on days 10, 17, and 24, respectively. Both acetoacetate and beta-hydroxybutyrate reabsorption rates increased linearly when plotted against their filtered loads. Thus, no tubular maximal transport rate exists for acetoacetate or beta-hydroxybutyrate during physiologic ketonemia. Conservation 450-500 mmoles of ketone bodies/day prevents large urinary losses of cations during prolonged starvation. Since ammonium becomes the major cation excreted during prolonged fasting, the increased renal reabsorption of ketone bodies minimizes body protein loss and aids in maintaining high circulating acetoacetate and beta-hydroxybutyrate concentrations.

Acetoacetates↗
PubMed1999

[Apoptosis--what is it? Significance in coronary heart disease and myocardial infarct].

Apoptosis is a physiological, highly conserved program of cellular suicide, characterized by nuclear condensation with DNA-fragmentation, by alterations in the distribution of cell membrane phospholipids, and by cellular shrink-age. Apoptotic cellular remnants engulfed by cell membranes are phagocytized largely without activation of inflammatory reactions. The apoptotic program is executed by a cascade of highly specific caspases, activated by complexation of initiatorcaspases in cytosolic signalling complexes at receptors of the TNF family or at impaired mitochondria. In many forms of cellular stress with damage of nuclear DNA and mitochondria, mixed forms of cell death are triggered with regulated activation of the apoptotic program and concomitantly, with induction of catastrophic necrosis. Such a mixed form of myocyte death is observed in myocardial ischemia and reperfusion. Antiapoptotic interventions can delay ischemic myocardial damage in experiments. Therefore, those interventions appear conceivable as future strategy for acutely enhancing the available time interval for therapeutic reperfusion. However, chronic inhibition of apoptosis for ongoing prevention of myocardial ischemic damage may not become a plausible strategy because of disturbances of the immune system, because of putatively infavorable effects on arteriosclerotic lesions and because of likely disturbances in the physiologic elimination of damaged mitochondria.

Apoptosis↗
PubMed2003

Influences of thermal acclimation and acute temperature change on the motility of epithelial wound-healing cells (keratocytes) of tropical, temperate and Antarctic fish.

The ability to heal superficial wounds is an important element in an organism's repertoire of adaptive responses to environmental stress. In fish, motile cells termed keratocytes are thought to play important roles in the wound-healing process. Keratocyte motility, like other physiological rate processes, is likely to be dependent on temperature and to show adaptive variation among differently thermally adapted species. We have quantified the effects of acute temperature change and thermal acclimation on actin-based keratocyte movement in primary cultures of keratocytes from four species of teleost fish adapted to widely different thermal conditions: two eurythermal species, the longjaw mudsucker Gillichthys mirabilis (environmental temperature range of approximately 10-37 degrees C) and a desert pupfish, Cyprinodon salinus (10-40 degrees C), and two species from stable thermal environments, an Antarctic notothenioid, Trematomus bernacchii (-1.86 degrees C), and a tropical clownfish, Amphiprion percula (26-30 degrees C). For all species, keratocyte speed increased with increasing temperature. G. mirabilis and C. salinus keratocytes reached maximal speeds at 25 degrees C and 35 degrees C, respectively, temperatures within the species' normal thermal ranges. Keratocytes of the stenothermal species continued to increase in speed as temperature increased above the species' normal temperature ranges. The thermal limits of keratocyte motility appear to exceed those of whole-organism thermal tolerance, notably in the case of T. bernacchii. Keratocytes of T. bernacchii survived supercooling to -6 degrees C and retained motility at temperatures as high as 20 degrees C. Mean keratocyte speed was conserved at physiological temperatures for the three temperate and tropical species, which suggests that a certain rate of motility is advantageous for wound healing. However, there was no temperature compensation in speed of movement for keratocytes of the Antarctic fish, which have extremely slow rates of movement at physiological temperatures. Keratocytes from all species moved in a persistent, unidirectional manner at low temperatures but at higher temperatures began to take more circular or less-persistent paths. Thermal acclimation affected the persistence and turning magnitude of keratocytes, with warmer acclimations generally yielding more persistent cells that followed straighter paths. However, acclimation did not alter the effect of experimental temperature on cellular speed. These findings suggest that more than one temperature-sensitive mechanism may govern cell motility: the rate-limiting process(es) responsible for speed is distinct from the mechanism(s) underlying directionality and persistence. Keratocytes represent a useful study system for evaluating the effects of temperature at the cellular level and for studying adaptive variation in actin-based cellular movement and capacity for wound healing.

Acclimatization↗
PubMed2000

[Tibial torsion deformities].

Tibial torsion defects are usually not clinically evident and, hence, are often overlooked. Clinical examination and CT scan have proved to be the best ways of measuring static tibial torsion, whereas dynamic measurements are usually performed in the clinic and the "gait laboratory." Only few studies have determined there to be a connection between a torsion defect in the lower leg and expected pathological conditions of the knee and ankle joints. However, patellofemoral instability, Osgood-Schlatter disease, osteochondrosis dissecans are increasingly being found in cases of increased external tibial torsion and arthrosis in reduced torsion. Although spontaneous correction may occur in certain cases, in others the only way to correct the condition is by employing physiologic torsion. Conservative treatment methods such as bandages or orthosis have been shown to not have any effect on torsion; thus, surgical treatment is the only successful way to correct a pathologic angle of rotation of the tibia. For this, supramalleolar osteotomy with fixation using Kirscher wires and plaster or an external fixator are the most common treatments.

Adolescent↗
PubMed2004

Responses of three heathland shrubs to single or repeated experimental trampling.

In the last few decades, trampling has become a cause of major disturbance to natural areas. Trampling can occur regularly either seasonally or throughout the year, or as a single impact depending on a recreational activity or an event. This study, carried out on a coastal heathland in north Brittany (France), was based on the hypothesis that the vegetation response can differ depending on whether the trampling is repeated or due to a single event. The aim was to compare the resistance and the short-term recovery capacity of selected species in coastal heathland communities subjected to a trampling experiment, applied once or five times (with equal total number of passes from 0 to 800). The temporal distribution of the trampling did not affect the response of Erica ciliaris, whereas for Erica cinerea and Ulex gallii, trampling was slightly less damaging when applied once rather than five times. These differences could be linked to the lower resistance and the higher recovery capacity of E. ciliaris, compared with the two other species. This study also emphasized the influence of site location by comparing observations with previous studies. Plant resistance calculated here appeared to be lower than that calculated for a less stressful site. The relationship between plant traits and response to trampling was also investigated. The effects of the different times between disturbance application and observations of the short-term response of woody vegetation to experimental trampling is also discussed.

Adaptation, Physiological↗
PubMed2006

Results of complete hemivertebra excision followed by circumferential fusion and anterior or posterior instrumentation in patients with type-IA formation defect.

To evaluate the results of surgical treatment in patients with unlocked full-segmented hemivertebra treated by excision. Twenty-six patients with a mean age of 12.4+/-1.7 years were included in the study. The mean duration of follow-up was 47.8+/-21.9 months. Diagnosis of type-IA hemivertebra was established by clinical, radiological, CT, and MRI evaluation. Preoperatively, patients were randomly allocated into two groups. In the first group, patients underwent anterior hemivertebrectomy initially; this was followed by posterior excision of the hemivertebra, posterior instrumentation, and fusion. In the second group, posterior components of the hemivertebra were excised at first, then the hemivertebra body was excised anteriorly, and this was followed by anterior instrumentation and fusion. For both groups, compression was applied to the convex side while distraction was applied to the concave side. Frontal and sagittal plane analysis of radiograms obtained preoperatively, postoperatively, and after a minimum period of 2 years was performed. The balance was analyzed clinically and radiologically by the measurement of the lateral trunk shift (LT) and shift of head (SH). The mean preoperative and postoperative Cobb angles were 45.5 degrees -/+11.4 degrees and 16.8 degrees -/+7.9 degrees, respectively, and postoperatively, a mean correction rate of 64.4+/-13.9% was obtained (P=0.00). The mean correction rate was 61.2+/-13.3% (19.2 degrees -/+7.6 degrees) for the last follow-up visit. Sagittal plane analysis demonstrated either conservation of physiological sagittal contours or a normalizing effect following excision of hemivertebra combined with anterior or posterior instrumentation. When postoperative balance values were compared, a statistically significant correction was found in terms of LT and SH values. Although none of the patients had complete balance (SH: 0 mm) or balanced curves (0 mm<SH<15 mm) preoperatively, 20 (76.9%) of the patients had a balanced trunk after surgical intervention. Circumferential fusion could be achieved in all cases. No neurological complication developed, the only complication was delayed wound healing. In view of these data, it is concluded that these techniques can be safely used for this patient group at low thoracic, thoracolumbar, and lumbar levels of vertebral column with high correction rates.

Adolescent↗
PubMed2007

Submergence tolerance in rice requires Sub1A, an ethylene-response-factor-like gene.

Submergence of rice (Oryza sativa) by flash flooding is a major constraint to rice production in Asia. Rice cultivars vary in their capacity to tolerate complete submergence; quantitative trait loci analyses have revealed that a large portion of this variation in submergence tolerance can be explained by one locus (Sub1) on chromosome 9. Two recently published papers (Takeshi Fukao et al. and Kenong Xu et al.) present evidence that a transcription factor belonging to the B-2 subgroup of the ethylene response factors (ERFs)/ethylene-responsive element binding proteins (EREBPs)/apetala 2-like proteins (AP2) within the Sub1 locus determines submergence tolerance in rice. These genes control highly conserved hormonal, physiological and developmental processes that determine the rate of elongation when submerged.

Adaptation, Physiological↗
PubMed2003

Fecal incontinence: evaluation and treatment.

Fecal incontinence affects men and women of all ages, leading to personal disability and high financial costs. The evaluation of the patient should clarify the pathophysiology of the symptoms and provide guidance in choosing the appropriate treatment. A comprehensive history and physical examination including endoscopic assessment is able to identify the cause of most cases of fecal incontinence. If necessary, functional methods can be used to confirm the diagnosis. Patient selection for suitable treatment is most important and should be based on clinical and physiologic findings. Conservative dietary or medical treatment is often effective, when the symptoms are mild. Biofeedback therapy is effective in most patients. It has no side effects and is well tolerated. Structural damage to the anus may be repaired by surgery, like sphincter repair, the best treatment of selective sphincter defects. Neoanal sphincters and artificial sphincters are the last possibility after failed surgery and before colostomy. They are less attractive because of technical difficulties and low success rate. A multidisciplinary approach to treatment has the potential to improve the outcome for patients with fecal incontinence.

Biofeedback, Psychology↗
PubMed1996

Ribosomal RNA: small nucleolar RNAs make their mark.

Small nucleolar RNAs direct the location of certain methylations in ribosomal RNA by direct base pairing; although evolutionarily conserved, the physiological significance of these modifications remains unclear.

Animals↗
PubMed2005

Evolutionary ecology of facultative paedomorphosis in newts and salamanders.

Facultative paedomorphosis is an environmentally induced polymorphism that results in the coexistence of mature, gilled, and fully aquatic paedomorphic adults and transformed, terrestrial, metamorphic adults in the same population. This polymorphism has been of interest to scientists for decades because it occurs in a large number of caudate amphibian taxa as well as in a large diversity of habitats. Numerous experimental and observational studies have been conducted to explain the proximate and ultimate factors affecting these heterochronic variants in natural populations. The production of each alternative phenotype is based on a genotypexenvironment interaction and research suggests that differences in the environment can produce paedomorphs through several ontogenetic pathways. No single advantage accounts for the maintenance of this polymorphism. Rather, the interplay of different costs and benefits explains the success of the polyphenism across variable environments. Facultative paedomorphosis allows individuals to cope with habitat variation, to take advantage of environmental heterogeneity in the presence of open niches, and to increase their fitness. This process is expected to constitute a first step towards speciation events, and is also an example of biodiversity at the intraspecific level. The facultative paedomorphosis system is thus ripe for future studies encompassing ecology, evolution, behaviour, endocrinology, physiology, and conservation biology. Few other systems have been broad enough to provide varied research opportunities on topics as diverse as phenotypic plasticity, speciation, mating behaviour, and hormonal regulation of morphology. Further research on facultative paedomorphosis will provide needed insight into these and other important questions facing biologists.

Animals↗
PubMed2002

Understanding the human condition: experimental strategies in mammalian genetics.

Mice have become the mammalian model of choice for the application of genetics in biomedical research due to the evolutionary conservation of physiological systems and their attendant pathologies among all mammals as well as the exceptional power of genetic research technologies in the species. Beginning from aberrant phenotypes, a large number of mouse mutants and natural polymorphisms have been cloned, providing much information about the molecular basis of physiological processes. Additionally, the variable expression of these mutations in different inbred strain backgrounds has demonstrated the importance of modifier genes, which are also susceptible to cloning. Research efforts are keeping pace with these developments. In the area of gene discovery, large, government-funded mutagenesis programs now exist, and as a matter of great practical importance, recent evidence suggests that the same genes may be involved in the natural polymorphisms affecting disease in mice and humans. In parallel, dramatic advances are also being made in our ability to measure physiological processes in mice, and the advent of expression profiling promises revolutionary advances in understanding phenotype at the molecular level. Gene-driven approaches have relied on engineering the mouse genome, including adding, subtracting, and replacing genes and, most recently, the ability to control gene activity reversibly. Together, these multiple advances in our technical abilities have created extraordinary opportunities for future discovery.

Animals↗
PubMed1994

Antibodies directed against monomorphic and evolutionary conserved self epitopes may be generated in 'knock-out' mice. Development of monoclonal antibodies directed against monomorphic MHC class I determinants.

Beta-2 microglobulin (beta 2m) gene 'knock-out' mice (C1D) were primed with purified H-2Kb and H-2Db molecules and spleen cells from immunized mice were used to generate monoclonal antibody secreting B-cell hybridomas. Approximately 0.2% of the Ig-secreting primary microcultures contained H-2b binding antibodies. Three stable anti-MHC class I (MHC-I) antibody secreting hybridoma clones were established and subcloned. All three MoAbs precipitated radiolabelled H-2 molecules as analysed by SDS PAGE, and all three MoAbs stained H-2b, H-2d, as well as H-2k cells by FACS analysis. The MoAbs stained to two beta 2m loss mutant cell lines, C4.4-25- and R1E, suggesting that some MHC-I heavy chain is exported to the cell surface even in the absence of endogenous beta 2m. Staining of murine cell lines kept under serum-free culture conditions was strongly influenced by the addition of bovine or human serum as a source of exogenous beta 2m suggesting that xenogeneic beta 2m affects the conformation of class I molecules. Furthermore, all three MoAbs strongly stained the peptide transporter deficient cell line, RMA-S, when cultured at 26 degrees C, however, staining was reduced five-fold when RMA-S cells were cultured at 37 degrees C. In total, these observations suggest that the MoAbs recognize conformational, presumably beta 2m and peptide dependent, self epitopes on MHC-class I. One of the three MoAbs stained rat blood mononuclear blood cells (BMC), all three MoAbs stained hamster BMC, whereas two of the MoAbs stained human cells. These data suggest that the MoAbs recognize determinants which are conserved between species. All three antibodies strongly inhibited the development of CTLs generated in an allogeneic one-way MLC, provided that the MoAbs were present during the first 24 h of culture. It is concluded that MoAbs reacting with monomorphic self epitopes may be generated using animals deleted of the gene of interest. The implications may be far reaching since such MoAbs potentially identify evolutionary conserved and physiologically important epitopes.

Animals↗
PubMed1996

A transformed human tracheal gland cell line, MM-39, that retains serous secretory functions.

Infection with the wild type SV40 virus was used to transform primary cultures of human tracheal gland serous (HTGS) cells. Over 80 different cell lines were obtained, but the majority had lost some of their epithelial and secretory features. However, one of these cell lines, MM-39, was shown to have conserved the physiologic characteristics of the genuine HTGS cells-i.e., the presence of cytokeratin, expression of cystic fibrosis transmembrane conductance regulator mRNA, a level of secretory leukocyte proteinase inhibitor secretion comparable to that of the native cells (25 +/- 3 ng/10(6) cells/h), and the responsiveness to pharmacological agonists: carbachol (+260 +/- 40%), isoproterenol (+260 +/- 40%), and adenosine 5'-triphosphate (+280 +/- 30%). These characteristics describe a transformed cell line of human tracheal gland cells which has retained the features of the native serous cells. As a result, this cell line appears to be a useful tool for large-scale physiologic and pharmacologic studies of bronchial secretion at the cellular level.

Cell Line, Transformed↗
PubMedDate not supplied

Parathyroid microautotransplantation and the viscerovertebral angle.

Conservation of physiologic values of circulating parathormone is a surgical objective in those instances in which a hyperfunctional parathyroid state exists as well as in those instances in which cervical evisceration employed as an ablative measure for the management of neoplastic disease threatens to impose postoperative tetany. Because the parathyroid glands may vary in number and in anatomic sites, a predictable and reproducible surgical approach that permits the operator an avenue of access to these structures is used. The viscerovertebral angle provides a surgical modality which facilitates the operative effort. The method has been applied in more than 70 patients.

Calcium↗